Polypeptide-catalyzed silica for dental applications

Polypeptides such as polylysine have been shown to catalyze the condensation and direct the structure of silica from precursor solutions under ambient conditions. Several of the reaction parameters have been shown to mediate this activity. Specifically, mechanical perturbation seems to play a role in the formation of hierarchical structures. Most studies have been conducted in solution, but biomedical and particularly dental applications will likely require control of biosilicified coatings, films or particle formation on surfaces. Tetraethylorthosilicate was reacted with polylysine and then spin coated onto a surface. The process parameters catalyst structure, pH, buffer: ethanol ratio and percentage of cocatalyst polyethyleneimine were varied to determine their effects on the formed silica. The chemical nature and morphology of the silica were investigated with FTIR and SEM, respectively and reaction rates were monitored with a colorimetric assay. Our results show that these process parameters had only minor effects on composition, but the catalyst conformation influenced the degree of hydration while the pH, choice of solvent and cocatalyst strongly influenced morphology. We also found that perturbation from spin coating significantly influences the silicification dynamics. The ability to catalyze nano- to micron-sized mineral with different morphologies using polypeptides could have numerous dental applications including, sealing of dentin tubules, in situ reinforcement of resin interfaces or preparation of implant surfaces.